Effect of Different Etching Times with Hydrofluoric Acid on the Bond Strength of CAD/CAM Ceramic Material

Abstract

The objective of this study was to evaluate the influence of hydrofluoric acid (HF) and conditioning time on the micro-shear bond strength (µSBS) between dual-cure resin cement and glass-ceramic materials, such as lithium disilicate ceramic (IPS e.max CAD, Ivoclar Vivadent) (EX) and leucite-reinforced ceramic (IPS Empress CAD, Ivoclar Vivadent) (EP), and also a hybrid ceramic (Vita Enamic, Vita Zahnfabrik) (VE). Eighteen sections with 1 mm thickness were cut from each CAD/CAM material and randomly divided into three groups, according to the surface etching time (30 s, 60 s, 90 s). The surface treatment was performed using 9.5% HF acid gel, then resin cement was applied on the prepared ceramic plates and light cured. µSBS values between resin cement and the ceramic material were measured with a universal testing machine at a crosshead speed of 0.5 mm/min until the failure occurred. The fractured surfaces of specimens were microscopically evaluated, and failure modes were classified as: adhesive between resin cement and ceramic, cohesive within ceramic or cement and mixed failure. Surface roughness of etched samples was examined using a scanning electron microscope. Obtained data were statistically analysed using one-way analysis of variance (ANOVA) and Bonferroni post hoc test with a level of significance α = 0.05. The results of the statistical methods applied indicate that µSBS mean difference for leucite-reinforced ceramic (EP) was statistically significant (p < 0.05). However, µSBS values for hybrid ceramic (VE) and lithium disilicate ceramic (EX) were not affected, from a statistical point of view, by the conditioning time (p > 0.05).

Influence of surface treatments and adhesive protocols on repair bond strength of glass‐matrix and resin‐matrix CAD/CAM ceramics

“…In addition, a previous study mentioned that treating EMAX with HF for 20 s according to the manufacturer's instructions increased surface energy and reduced contact angle for adhesives, providing ideal microporosities for mechanical interlocking 42 . For standardization purposes, in the present study EMAX was etched for 60 s since it was reported that this duration provides the highest bond strength for EMAX and VM, 25 and several studies revealed that the etching time whether it is 20,30,40,60, 90, or 120 s do not have a significant effect on the μSBS values obtained for EMAX 24,26 . Despite the difference in etching time, similarly, HF + SA application on EMAX enhanced μSBS significantly and increased the percentage of mixed and cohesive failure types in the present study.…”

“…After the aging protocol, specimens were randomly separated into four main groups as follows: Control: no treatment was applied on the specimen surface. AL: Specimen surfaces were sandblasted from 10 mm above, with a sandblaster (Airsonic, mini sandblaster; Hager Werken) at a pressure of 1.5 bar using aluminum oxide powder (Cobra; 50 μm Al 2 O 3 , Renfert GmbH, Hilzingen, Germany). And they were rinsed with distilled water for 30 s and dried with oil‐free air to clean the residues. HF: The specimen surfaces were etched with 9% hydrofluoric acid (Ultradent) for 60 s 24–26,41 and then were rinsed and air‐dried with an oil‐free air/water syringe. MEP: Monobond Etch and Prime was applied gently with a micro brush and rubbed for 20 s. After waiting for 40 s, it was washed off and air‐dried for 10 s. …”

“…• HF: The specimen surfaces were etched with 9% hydrofluoric acid (Ultradent) for 60 s [24][25][26]41 and then were rinsed and air-dried with an oil-free air/water syringe.…”

“…[21][22][23] However, it can cause respiratory tract irritations when applied intraorally and cause great volume losses, surface and subsurface cracks, and microchipping when applied with high pressure on the resin-matrix and glass-matrix ceramic restorative materials. [21][22][23] As a method of chemical surface treatment, the use of hydrofluoric acid (HF) etching is also widely accepted, [24][25][26] and along with a silane, it is considered to provide the most reliable bond strength for glass-ceramics. 4,27,28 However, HF is highly hazardous because of its corrosiveness, reactivity, and toxicity.…”

Effect of Surface Pre-treatments and Thermocycling on Microtensile Bond Strength of Lithium Disilicate Glass Ceramics to Self Adhesive Resin Cement

“…On the other hand, Avram et al 24 found that machinable e max CAD ceramic achieved superior results when etched with 9.5% HF acid for 60s. Moreover, no significant differences were found between the bond values of etching time (30 s and 60 s) which led to the fact that; for lithium disilicate ceramic bonding, it is possible to use either a higher concentration HF acid with the recommended manufacturer' time or a higher etching time with the acid concentration recommended by manufacturer.…”